生成3个随机的ad.innerHTML HTML代码

I have a script below and I want to modify row 19 to show 3 different predefined html tags. Can someone show me how to do that?

Thanks.

<script> 

  // Run after all the page elements have loaded
  window.onload = function(){ 

    // This will take care of asynchronous Google ads
    setTimeout(function() { 

      // We are targeting the first banner ad of AdSense
      var ad = document.querySelector("ins.adsbygoogle");

      // If the ad contains no innerHTML, ad blockers are at work
      if (ad && ad.innerHTML.replace(/\s/g, "").length == 0) {

        // Since ad blocks hide ads using CSS too
        ad.style.cssText = 'display:block !important'; 

        // You can put any text, image or even IFRAME tags here
        ad.innerHTML = 'Your custom HTML messages goes here';      
      }

    }, 2000); // The ad blocker check is performed 2 seconds after the page load 
  }; 

</script>

I got the answer!

    <script>          
      // Run after all the page elements have loaded
      window.onload = function(){         
        // This will take care of asynchronous Google ads
        setTimeout(function() {               
          // We are targeting the first banner ad of AdSense
          var ad = document.querySelector("ins.adsbygoogle");             
          // If the ad contains no innerHTML, ad blockers are at work
          if (ad && ad.innerHTML.replace(/\s/g, "").length == 0) {              
            // Since ad blocks hide ads using CSS too
            ad.style.cssText = 'display:block !important';  
            //Add variables
            var Ads = ["Ads 1", "Ads 2", "Ads 3"];
            var displayAds = Ads[Math.floor(Math.random() *Ads.length)]; 
            // You can put any text, image or even IFRAME tags here
            ad.innerHTML = displayAds;            
          }           
        }, 2000); // The ad blocker check is performed 2 seconds after the page load 
      };          
    </script>